Epidemiologic Notes and Reports Measles -- El Paso,
Texas, 1981

In the period March-June 1981, 219 cases of measles were
reported
by the El Paso (Texas) City-County Health Department. All patients
had a temperature of at least 101 F (38.3 C), a rash of at least 3
days' duration, and at least 1 of the following: cough, coryza,
conjunctivitis, or Koplik's spots. Twelve cases were confirmed by
a
4-fold rise in complement fixation (11) or hemagglutination
inhibition
(1) antibody titers between acute- and convalescent-phase serum
specimens.

Rash onset occurred between April 11 and May 8 in 154 (70.3%)
of
the cases. Patients ranged in age from 3 months to 36 years. The
largest number of cases, 81 (37.0%), occurred among 15-19 year olds
followed by 67 among 0-4 year olds (Table 1). Of these 67
pre-school
patients, only 9 (13.4%) attended day-care centers.

Of the 219 patients, 94 (42.9%) had histories of adequate
measles
vaccination*; 85 (38.8%) had no history of prior vaccination; and
37
(16.7%) had histories of inadequate vaccination. The vaccination
status was unknown for 3 patients.

Five of the 9 El Paso County public school districts were
involved
in the outbreak. The highest attack rate, 2.3 cases/1,000
enrollees,
occurred in the Ysleta Independent School District, where 63 of the
100 cases reported occurred in a single high school (Figure 2). On
April 28, 776 (34.3%) of the 2,265 students at that high school
were
identified as being susceptible, and a special clinic was conducted
at
the school on the morning of April 29. Only 6 cases were reported
after the clinic date, and no cases were reported 14 days or more
(1
incubation period) after the measles vaccination clinic.

On April 29, the El Paso City-County Health Director formally
declared an epidemic. All schoolchildren in the county were
required
to show proof of adequate measles vaccination or physician-verified
measles illness. Over 120,000 school records were screened in
public,
private, and parochial schools. The majority of schools excluded
students who were unvaccinated. Because of staff limitations, the
health department elected to conduct vaccination clinics only at
those
public schools with at least 300 susceptible students. Special
clinics were conducted at 14 of the county's 23 high schools, and,
at
the same time, regular clinic services and immunization services
were
maintained for the entire day in the public health clinics.

Editorial Note

Editorial Note: Texas school immunization laws, rules, and
regulations (as amended in 1978) provided for a graduated
implementation of requirements for measles vaccination. For the
school year 1980-1981, only students through the 7th grade (13
years
of age) were required to show proof of measles protection. The
lack
of such regulations for middle and high school students probably
explains the high attack rate in El Paso County in persons 15-19
years
of age.

Based on experience in the El Paso outbreak, school regulations
for the state of Texas were revised so that, effective September 1,
1981, a history of physician-verified measles or a history of
adequate
vaccination for measles would be required for all students to
attend
school, including high school. In May 1981, it was estimated that
approximately 290,000 students in public junior and senior high
schools would need measles vaccination as a result of the rule
changes. From September 1 to November 30, 1981, a statewide record
review of all junior and senior high school students was conducted,
and from August 1 through November 30, 1981, 112,696 doses of
measles
vaccine were administered through public health clinics to students
10-19 years of age, an increase of 646% over the same period in
1980.
It is now estimated that 98.3% of the 2,919,150 students currently
enrolled in the 1,098 school districts in Texas from kindergarten
through grade 12 are in compliance with the new state immunization
requirements.

The cornerstone of the measles elimination effort is the
achievement and maintenance of high immunization levels, and school
requirements for all children from kindergarten through l2th grade
are
fundamental for success (1). Past studies have demonstrated that
states with such regulations have the lowest incidence rates for
measles (2-4) and that enforcement of these regulations with
exclusion
of non-compliant students correlates best with low measles
incidence
(3).

CDC. School immunization requirements for measles--United
States
1981. MMWR 1981;30:158-60.
*Defined by the health department as vaccine administered after 12
months of age and after January 1968.

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